Conventionally, carbon materials such as graphite, carbon nanotubes, carbon fibers, or carbon particles have been widely used as reinforcing agents or fillers in resins. In addition, in recent years, exfoliated graphite having a smaller number of stacked layers of graphene obtained by exfoliating graphite has attracted more attention.
As composite materials of the carbon materials as described above and resins, for example, a composite material is known which is obtained by dispersing a carbon material such as carbon fibers in an epoxy resin as shown in the following Patent Literature 1.